Monitoring the adhesion process of tendon stem cells using shear-horizontal surface acoustic wave sensors

摘要

Cell adhesion to a substrate or extracellular matrix (ECM) plays an important role in a variety of cellular functions, such as cell migration, proliferation, differentiation, and tissue formation. Shear-horizontal surface acoustic wave (SH-SAW) sensors can detect cell behaviors in liquid in a non-invasive, simple and quantitative manner. As the key part of SH-SAW, acoustic-wave guiding layer plays a crucial role in improving sensor performance. Parylene-C (poly(2-chloro-p-xylylene)) has been proven as ideal guiding layer due to its good uniformity, compactness and adhesion to substrate. Of comparable cell and protein compatibility to the tissue culture substrate, parylene-C films also have preferable effects as the bio-sensitive interface on SH-SAW sensors. In this study, SH-SAW sensor with parylene-C acoustic-wave guiding layer was adopted to monitor the adhesion process of tendon stem cells (TSCs), a newly discovered stem cell type in tendons. TSC suspensions of different concentrations (0.5×10~5, 1.0×10~5, 2.0×10~5, 4.0×10~5 cell/ml) were added to collagen-coated PDMS wells successively. The cells were maintained in the incubator for 10 hr, during which corresponding S21 spectrums were recorded every 1 min. The results indicated that there was a sharp increase in S21 loss in the beginning of incubation. With incubation continued, the increase rate reduced gradually, and S21 loss tended to be stable. S21 phase decreased continuously at first, and then entered a plateau with continued incubation. These changes are considered to be related to the integrin-ECM protein interactions and focal adhesion formation occurring in TSC adhesion process. In addition, as TSC suspension concentration increased, the final value of S21 loss change due to TSC adhesion was increased. SH-SAW sensors exhibit high sensitivity and stability in TSC adhesion monit- ring, indicating their potential for investigating cell biology in general and cell adhesion in particular.